MAPREDUCE-5065. DistCp should skip checksum comparisons if block-sizes are different on source/target. Contributed by Mithun Radhakrishnan.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1468629 13f79535-47bb-0310-9956-ffa450edef68
Fix HADOOP-9467 attribution.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1468731 13f79535-47bb-0310-9956-ffa450edef68